December 01

Diesel Fuel & How To Winterize It

If you operate in the northern portion of the United States, winterization of your diesel fuel should be considered a top priority to keep you moving through the winter. Not knowing how to winterize diesel fuel properly is simply not being operationally prepared. At certain temperatures, diesel will turn into a gel-like substance that will not flow through your fuel system. Not only will it gel in your tanks, fuel lines, and fuel filter, it can stop you in your tracks, prevent you from getting moving in the morning, and prevent you from getting heat in your cab/sleeper, which presents a serious safety hazard.

It isn’t easy to find a specific temperature for diesel gels because so many variables come into play. Two temperature points are concerning:

  • Cloud Point – the point at which paraffin wax just begins to precipitate out of the fuel. The fuel will start to become cloudy, but the actual temperature can vary somewhat.
  • Pour Point – also referred to as the gel point, is the point at which wax precipitates out of the fuel that it no longer flows. The gel point is generally ten to fifteen degrees below the cloud point.

Let’s look at the different types of crude oil, diesel, and their temperature characteristics. All petrodiesel contains paraffin waxes, which are straight and branched-chain hydrocarbons. It’s these waxes that become solid at lower temperatures. The amount of paraffin wax in your diesel depends on the crude oil used and the process to manufacture the fuel. Crude oil is classified as:

  • Brent Blend – is broken down into Brent Crude and Brent Light Sweet Crude.
  • West Texas Intermediate – also known as Texas Light Sweet.
  • OPEC Reference Basket – is broken down further as Bonnie Light, Arab Light, Basra Light, Saharan Blend and Minas.
  • Dubai Crude

Diesel fuel comes in two blends: summer and winter. For this discussion, summer blend diesel is non-treated diesel. In this case, the paraffin wax will begin to precipitate out as the ambient temperature drops below +32F. As the ambient temperature drops below 0F, the solidifying wax particles combine into solids large enough to be stopped by filters. Summer blend diesel, also called #2 ULSD, will cloud and gel at higher temperatures than winter blend #2 ULSD, a mixture of #2 ULSD and #1 diesel/kerosene. It is the kerosene that lowers the gel point in winter blend diesel. The actual temperature at which your winter blend diesel will gel depends on the specific mixture you purchased. The higher the kerosene content, the lower the gel point.

If you are fueling in a part of the country that is running a petrodiesel/biodiesel blend, you should be aware that biodiesel will gel at a higher temperature than petrodiesel. Biodiesel comes in B2, B5, B20, and B100. That number represents the percentage of biodiesel in the mix. Like petrodiesel, the approximate temperature at which pure biodiesel will gel depends on the oil it’s made from. Some typical oils include peanut, corn, soy, coconut, olive, and canola. Biodiesel from canola oil has the lowest gel temperature. A petro/biodiesel mix will have a lower gel point than pure biodiesel. A petro/biodiesel mix can be treated to lower the gel point just the same as petrodiesel.

All diesel has water suspended in the solution. This water comes from condensation that forms inside a cold fuel tank with warm fuel. You can also get condensation from temperature and humidity changes. Keeping your diesel as “dry” as possible by using a water separator is an excellent way to pull the water out of your fuel. As the temperature drops and the paraffin wax begins to precipitate out of the fuel, the water held in suspension will start to form ice crystals that can cause excessive wear and damage to your fuel system and engine components.

There are several ways to prevent diesel clouding and gelling. I’ve seen insulated fuel tank blankets used in some climates. The most common is to add a winter fuel additive. There are additives to address the moisture content by helping to “dry” the fuel; there are additives that lower the gel point of diesel fuel, and there are combination additives. Some additives will thaw your diesel after it has gelled, but that can be somewhat difficult on the side of the interstate with the temperature in the teens or below as it requires removing the fuel filter, sometimes more than once. The method you choose is your preference.

Most truckstop chains treat for the conditions of the region they are in. Check with your engine manufacturer to get their recommendations on fuel treatments, as some can cause damage to the new high-pressure standard rail injection systems.

The point is to prepare ahead of time, and if you are operating in cold climates, it might be wise to treat your fuel. It is much cheaper than a tow and recovery bill. It is also worth noting that it’s possible to buy fuel in a relatively warm climate in the morning and finish your day in a cold environment. Be prepared and proactive in keeping your diesel flowing.

Source: ATBS